Optical apparatus



June 29, 1937. J. F. LEVENTHAL 2,085,594

OPTICAL APPARATUS Filed Aug. 11, 1951 3 Sheets-Sheet 1 w Xi l f- 7 4,4:

INVENTOR ATTORNEYS.

OPTICAL APPARATUS v Filed Aug. 11, 1931 3 Sheets-Sheet 2llllllIIHIHIIHIIIIIIIIIIIIIV N INVENTOR Q7 kg W 3% ATTORNEYS June 29,1937. J. F. LEVENTHAL OPTICAL APPARATUS 3 Sheets-Sheet 3 Filed Aug. 11,195i INVENTOR ATTORN EYS Patented June 29, .1937

11 STATES OPTICAL APPARATUS Jacob F. Leventhal, New. York, I N. Y.,assignor to Leventhal Patents, Inc., New York, N. Y., a corporation ofDelaware Application August 11, 1931. Serial No. 556,358

4 Claims.

This invention relates to motion picture apparatus and more especiallyto an optical compensator for'producing stationary images of pictures ona film advanced at uniform rate of 5 speed.

In some systems, the optical compensator used for this purpose iscomposed of a plurality of plane-parallel refracting members which arerotated about an axis in synchronism with the 10 linear movement of thefilm. Such compensators produce various kinds of objectionableaberrations, the magnitude of which is proportional to the compensationefiected by each refracting member. It is an object of this invention toso 15 reduce in magnitude the aberrations produced by such opticalcompensators as to make them unobjectionable.

- According to the invention each picture .is

compensated in a plurality of stages by successively operativerefracting members and separate optical means successively effective areprovided for producing successive co-extensive stationary images of thepicture. The magnitude of the aberrations is proportional to thecompensation 25 I effected in each stage rather than to the compensationof the entire picture and the aberra tions are therefore so reduced asto be unobjectionable.

Other objects, novel features and advantages t is a diagrammatic viewillustrating the 4 principle or operation of the device;

Fig. 5 is a section similar to Fig. 2 of a modifled form of apparatus;

Fig. 6 is a partial diagrammatic section oi the modification shown inFig. 5; 45 Fig. 7 is a view similar to Fig. 2 of a further modifiedform. of apparatus;

Fig. 8 is a fragmentary diagrammatic section of the apparatus-shown inFig. '7; and

Fig. 9 is an elevation of Fig. 8. v

the driving belt l3. shaft ii and supports a plurality of plane-paral-65 lei retracting members 85. symmetrically ar A. frame it supports ashait it on which is mounted a driving pulley i2 over which is passedAholder it isfixed to the.

ranged with respect to the axis of rotation and having theiriacesparallel to said axis.

A second frame It rotatably supports a shaft ii to which is fixed asprocket l8 and a pinion it which meshes with a pinion Illa fixed to the5 shaft it. Above the sprocket Hi there is provided a gate 20 throughwhich motion. picture film F is drawn by means of the sprocket iii. Acondenser lens 2! is provided for directing light from the source 22through the film and 10 the refracting members l5. The gear ratiobetween the pinions l9 and iilais such that the film is advanced throughthe height of one pic- Y ture While the holder I4 makes a fractionalrevo lution equal to the ratio of two refracting members to the wholenumber. In this particular instance, the holder is provided'with eightrefracting members so that it makes of a revolution while the film isbeing advanced one picture.

With this arrangement, each picture is compensated in two stages, thefirst compensating stage being effected by one refracting member and thesecond compensating stage being effected by the following refractingmember; An objective lens 23 images the compensated pictures. The firstretracting member compensates the picture while the same isbeingadvanced. a distance equal to one half of its height and produces astationary virtual image of the picture, 30 the central point V1 ofwhich is spaced a predetermined distance from the optical axis of theapparatus in the direction of film travel. The second retracting memberalso produces a stationary image of the picture, the midpoint V2 of 35which is spaced from the optical axis the same distance,-- butoppositely from the image producedby the first refracting member.

Real images of the compensated pictures are formed by the lens 23 andare made co-extensive in the same plane by means of a pair of mirrors 24and 25 set at different angles and to which the light path is directedby a reflecting prism 25. A shutter}? is mounted on the shaft l l and isprovided with apertures 25.? and 29 to permit "light to pass to one ofthe mirrors while block-' ing off light-from the other mirror. Theseapertures are so arranged that light passes to one of the'mirrors duringthe first stage of compensa- The operation is diagrammaticallyillustrated 5 During this time the mirror 25 is rendered inoperative byreason of being blocked off by theshutter 21. By means or the mirror 25,the real image of the picture is formed at I during the period that thesecond refracting' member is ef- -iective. During this period the mirror24 is inoperative as it is blocked off by the shutter 21. Thus,successive co-extenslve images of the same picture are produced duringthe two compensating stages and'while the picture is advanced a distanceequal to its own height. The aberrations are so reduced as to beunobjectionable due to the fact that the magnitude of such aberrationsis proportional to the compensation effected in each compensation stagerather than to the entire compensation of the picture.

In Figs. 5 and G'there is disclosed a modified form of shutter and themirrors are provided with means for adjusting their angularity. 'I'heshutter consists of a drum 30 mounted on a shaft 3| rotatably supportedby the bearings 32 of the frame Ill. The periphery of the drum tapersinwardly so as to conform generally to the mirror surfaces and isprovided with a pair of slots 33, each of substantially in length andeach being arranged in register with one of the mirrors 24a and 25a.Thus, during one-half the rotation of the drum 30, the mirror No isexposed and during the other half of the drum's rotation, the mirror 25ais exposed. The mirrorsare pivotally supported by a bracket 34 extendingfrom the frame ill and screws 35 provide means for adjusting theangularity of the mirrors. The shaft t! is driven from the shaft H bygears Ha, Nib, 890, Md, Me and ill at four times the speed of the latterso that the shutter makes one complete revolution during .icompensationof a single picture.

6 and l disclose a further modification oi the shutter. In thismodification, the mirror 22th is stationary and is supported Toy theframe it While the mirror '25?) is mounted on a shaft rotatablysupported lay-bearings 3i supp e ed by" the frame The mirror is sulost asemi-circular in and is arr ngedto front of the mirror 32th so of eachrevolution oi? the shaift is obscured by the mirror more, duringone-half of its revolut' ror W5?) lies outside the light pa period itinoperative. period in which the mlrro operative. The =1 he shaft it bysuitable at four times sp as previously compass It is of courseunderstood that various modiflcations may be made in the apparatus abovedescribed without in any way departing from the spirit of the inventionas defined in the appended claims.

I claim:

-1. In a device of the character described, means for feeding motionpicture film at uniform linear speed, rotatable plane-parallelrefracting means arranged and adapted upon rotation in timed relationwith the movement of the film to produce two successively stationary Ispaced virtual images of a luminous point on the moving film, means torotate said retracting means in timed relation with the movement of saidfilm, a lens for producingreal images of said spaced virtual images, areflector individual to each real image and cooperating with said lensto effect registration in a common image plane of said real images, arotatable apertured drum surrounding said reflectors, and means torotate said drum in synchronism with said refracting means foralternately masking and unmasking said reflectors.

.2. In a device of the character described,

means for feeding motion picture film at uniform linear speed, rotatableplane-parallel retracting means arranged and adapted upon rotation intimed relation with the movement of the film to produce two successivelystationary spaced virtual images of a luminous point on the moving film,means to rotate said refracting means in timed relation with themovement of said film, a lens for producing real images of said spacedvirtual images, a reflector individual to each real wherebya point onthe moving film is rend ed optically conjugate successively with ea "1 istationary points lying in a COIG" son 1" being spaced in the directionlens, a first and a second reflector .i spectively to said spaced pointsand cooperative with lens to est acy successively betwr each of said ishoptic sec-o tion 0 erlying said second for rotating said being spaced inthe direction of film travel, a lens, a first and a second reflectorindividual respectively to said spaced points and individuallycooperative with said lens to establish optical conjugacy successivelybetween a stationary third point and each of said spaced points duringenemas Y 4 3 stationary points lying in a common plane and conjugacythereof with the moving film point, a rotatable apertured drumsurrounding said reflectors, and means to rotate said drum insynchronism with said compensating means for a1- ternately masking andunmaski'ng said reflectors.

JACOB F.

